This invention relates to apparatus for equipping circuit boards with electronic components, and it relates, more particularly, to apparatus wherein the terminal pins of the components are inserted in openings in the circuit board lying on an anvil. The anvil serves the purpose of bending and severing the terminal lugs by means of suitable cutting tools each consisting of a stationary and a movable knife. In addition, the apparatus includes monitoring devices provided for the terminal pin ends protruding from the terminal openings on the side of the circuit board opposite the components.
When inserting, for example, four-to-forty pin integrated circuit components by automaic mounting machines, plugging errors may occur. The pins of the components are typically in the form of metal lugs that tend to stand individually outside their contacting hole region and bend while being inserted. This results in the undersired consequence of faulty contacting. Therefore it has heretofore been the general practice to subject all automatically mounted flat modules to a visual inspection after the inserting operation, testing in particular for pairing of the inserted pins per component.
To simplify the foregoing described visual inspection, recent practice has been to reproduce the terminal lugs on neutral paper by means of carbon paper and rubber press-on rolls, thereby simplifying the inspection. From German Patent Document DE-OS Pat. No. 33 18 110, there is disclosed apparatus for equipping circuit boards, to provide the respective anvil with an optical monitoring system for the terminal lug ends protruding from the openings on the side of the circuit board opposite the components. Besides it is also disclosed in German Patent Document DE-OS Pat. No. 33 40 147, which has also been filed here as a corresponding patent application and has matured into U.S. Pat. No. 4,570,336 issued on Feb. 18, 1986, to divide at least one of the knives into separate cutting tongues by parallel slits on the cutting edge side, each tongue associated with a strain gauge whose signals can be picked up in an evaluating unit.
The later device has the advantage that the pressing and bending forces acting during cutting against the stationary cutting areas generate, via the strain gauges associated with the cutting areas, an electrical signal for each terminal pin directly. This signal may be displayed on a display unit and can be evaluated accordingly. This method has proved successful in the practice already. The unavoidable trade-off is that the knives of the cutting tool must be replaced regularly and for each new knive the difficulties associated with applying, contacting and protecting the strain gauges must be heeded to prevent damage to the gauges.